And I need to preface that question. Back in the day when I used to live there (the golden years of the Twins - 87-92) the sports fandom in Minny as far as the four major sports were concerned went like this:
- Everyone loved the Vikings and that was it. Period. And Burnsie was cool
- Everyone loved the Twins (and they were the talk of the town - after Prince- because those titles)
- When the Wolves came it was more like a novelty (Pooh Richardson, Sidney Rice, Eric Musselman years).
- As far as the Northstars were concerned, most people at that point were more concerned about getting on their broomball shoes and having a decent game (until Dino Ciccarelli allegedly exposed himself and that was made into oofda big time news)
These days my take is that:
- Everyone still cares about the Vikings (but does not hate the Packers or the Bears as much as before)
- The Twins are kinda fun thing to watch especially with that nice park; and if they win the division is fine and good- unless they are not winning
- The Wolves are so good because they are winning - unless they are not winning
- The Wild are so good because they are winning - unless they are not winning
And I am talking about the average Minny person out there who considers themselves a "sports fan".
Am I too much off?

I don't think that is necessarily the case. I think there are your casual fans whose absence in the stands and lack of time spent otherwise following the team will be noticeable when things aren't going well. But as least for the Twins, Vikings, and Wild I think there is a very solid base of die hard fans that are in it for the long haul. I am very happy about the Timberwolves success this year. However, I think they would be the one franchise in the Twin Cities where the bandwagon argument would be most applicable. After they stopped making the playoffs and Garnett left, they were almost completely abandoned by the entire fan base. Hopefully, the energy that Love and Rubio have injected into the franchise will get the fan base back to where it needs to be for years to come!

Absolutely they/we have become bandwagoners! When a region goes 21 years without so much as one championship game/series appearance, I think it's only natural that fans lose interest and then regain that interest when a team recaptures some magic and goes on a nice run. Sure there are the hardcore fans that are going to stick through thick and thin, like those of us hanging out on this forum, but the casual fan isn't going to follow a horrible team. Winning makes people happy. Losing makes people sad. Why would you sit through a long spell of losing seasons unless you're super passionate about a team? I imagine people in Washington are probably on the same level as Minnesotans, while Bostonians will never get labeled as bandwagoners these days due to so much success across the board.

Absolutely they/we have become bandwagoners! When a region goes 21 years without so much as one championship game/series appearance,.

You are an expat, like me , so that might not count too much. But I really loved that comment because one of my sayings is that kids who were born the last time the Twins won it all they are now old enought to vote (that was a bit ago) or buy beer. But methinks that the locals are a tad more complacent... and winning the division and three and out in the postseason is all spiffy good.